The present invention relates to tub grinders and in particular a tub grinder in which the swing diameter of the hammer mill incorporated therein is adjustable.
Tub grinders are used for chopping or grinding various materials to facilitate handling, disposal or processing. Tub grinders generally comprise a stationary floor with a cylindrical side wall which rotates relative to the floor. Projections or fins extending inwardly from the sidewall engage material positioned in the tub causing the material to rotate with the cylindrical side wall relative to the floor. A hammer mill having a plurality of hammers extending radially outward is rotatably mounted below the floor of the tub grinder such that the hammers extend above the floor and into contact with the material to be ground during a portion of the hammers path of rotation.
Traditionally, tub grinders have been equipped with a hammer mill having a fixed swing diameter. However, variations in the properties of the material to be ground can significantly affect the efficiency of the tub grinder. Therefore, existing tub grinders are limited in the type or size of materials they can process efficiently. For example, for some materials, the depth of cut provided by the hammer mill will be too deep causing the machine to bog down. For other materials, the same hammer mill will take in less material than it is capable of efficiently processing, adding time and cost to the grinding process.
Due to the costs of tub grinders, it is generally impractical for the operator to purchase different tub grinders for processing different materials. The operators generally must base their purchasing decision on the efficiency of the particular hammer mill (based in part on its hammer mill swing diameter) in processing the material most commonly processed by that operator. There remains a need for tub grinders which provide greater flexibility in efficiently processing different materials.